Digital mobile telephony has become one of the most important ways of communicating, both for making voice calls and exchanging data. For the mere purpose of exchanging data, network protocols have also evolved for use by means of computers, e.g. in Wireless Local Area Networks (WLAN).
A system for short range radio communication between electronic devices has also been provided under the name Bluetooth™. Bluetooth is basically a wireless personal area network technology, which is an open standard for short-range transmission of digital voice and data between predominantly mobile devices, and supports point-to-point and multipoint applications. Bluetooth typically provides up to 720 Kbps data transfer within a range of 10 meters and up to 100 meters with a power boost. Bluetooth uses omni-directional radio waves that can transmit through walls and other non-metal barriers in the unlicensed 2.4 GHz band.
In recent years, a new technology for even shorter range communication in the mobile telecommunications market has evolved, based on radio frequency identification (RFID) and generally referred to as Near Field Communication (NFC). NFC has been characterized as the intuitive link between consumer devices, and facilitates short-range communication between electronic devices, such as mobile phones, Personal Digital Assistants (PDA), computers and advanced consumer electronics, via a fast and easy wireless connection. The NFC technology has been developed jointly by Royal Philips Electronics and Sony Corporation, and enables consumers to securely exchange and store all kinds of information including ownership rights, credit card numbers, coupons, membership messages, pictures and MP3 files, simply by bringing two devices close together. NFC may act as a secure smart key for access to content and services such as cashless payment, ticketing, online entertainment and access control, and can also be used to automatically configure and initiate wireless connections under other protocols, such as Bluetooth or Wi-Fi, enabling devices to communicate at longer ranges or transfer data at higher rates.
Typically, NFC provides a contactless proximity interaction over a few centimeters which simplifies the issue of identification, as there is less confusion when devices can only connect with their immediate neighbors. A number of NFC trials are currently taking place around the globe. Since December 2005, a major NFC trial has been underway at the Philips Arena stadium in Atlanta, Georgia, allowing sports fans to easily buy goods at concession stands and apparel stores. Additionally they are able to access and download mobile content such as ring tones, wallpapers, screensavers and clips from favorite players and artists by holding their NFC-enabled phone in front of a poster embedded with an NFC tag.
NFC runs on the 13.56 MHz frequency band with a read and write range of up to 10 centimeters. It operates at data rates of 106 kbits/s and 212 kbits/s, although higher transmission speeds can be achieved between dedicated NFC devices, initially up to 424 kbits/s with potential for higher bit rates. As NFC devices can operate in an active or passive mode, the technology also offers a unique link to the contactless smart card world as it is compatible with the broadly established contactless smart card infrastructure based on ISO 14443 A (i.e. Philips MIFARE® technology), as well as Sony's FeliCa™ card used for electronic ticketing in public transport and for payment applications. It also allows mobile devices to communicate in passive mode, saving power and extending battery life. Targeted to become a widely adapted contactless infrastructure, NFC is already standardized according to globally accepted standardization bodies, such as ISO (18092), ECMA (340) and ETSI. As is often the case with the devices sharing a single RF band, the communication is half-duplex. The devices implement the “listen before talk” policy—any device must first listen on the carrier and start transmitting a signal only if no other device can be detected transmitting. Furthermore, the NFC protocol distinguishes between the Initiator and the Target of the communication. Any device may be either an Initiator or a Target. The Initiator, as follows from the name, is the device that initiates and controls the exchange of data. The Target is the device that answers the request from the Initiator. The NFC protocol also distinguishes between two modes of operation: Active mode and Passive mode. All devices support both communication modes. The distinction is as follows:
In the Active mode of communication both devices generate their own RF field to carry the data.
In the Passive mode of communication only one device generates the RF field while the other device uses load modulation to transfer the data. The protocol specifies that the Initiator is the device responsible to generate the RF field.